Process of separating antimony and lead



. fume rrom the,

l atented Apr. 28, 1925.

UNITED BURT o. sTANnAnn/or'BERknLEY, AND CALVIN w. ,IHAFFEY, or sEnBr;CALIFORNIA;

I TO AMERICAN ,SMELTING- ANiD REFl N-INGaCaMPANY, OF NEW YIQRK,

nn, A' oonrolmm101a or N W JEB Y- 1 a rnocnss orsnmnnrrn'o immotiqi im INo Drawing. i

To all whom it concern Be it known that wef'BURT C; STANNA-Rnf a citizenof the United States, and a resident of Berkeley, in the county ofAlameda and- State "of California, and .CALVIN WV. "HAFFEna citizen ofthe United States, and a resident ofSelby, in the county of Contra Costaand a State of California, have in-' vented certain new and 'usefulImprovements in Processes of Separating Antimony and Lead, of; which thefollowing is a specification. l W

The invention relates broadly to a process for separating antimony intheform of a relatively pure fantiniony oxide from lead bullion and alloysfor thepurpose ofsoftcningandpurifying the lead and ofobtaining metallicantimony. 4 J

The bullion or matte obtained from the treatment of plumbife'rous oresalways contains in addition to the-lead various other metals orcompoundssuch as antimony copper, arsenic, tiny bismuthand frequently.more or less silver andgold. All of the \known processes for separatingthe anti- I many and the lead, such as liquation oxi dation andcupellation produce a dross slag which rises to the top of'the bath andis removed by skimming. Frequently a large number of skimmings must betaken off before the lead is sufliciently pure for com:

mercial use, and" relatively large quantities of lead are alwaysenmeshed with the several skiinniings which are recovered only at thecost .onfi subsequent extensive treatment.

Our" invention relates to a process whereby lead hullion containing arelatively high percentage of antimony may be treated to separate thegreater part of the antimony without producing slag or dross in largequantity and without removing any appreciable e mount of the lead untilsubstantially allkof t .e antimony above a relatively fixed minim .namount has been removed as a loath containing the impure bullonor alloy.I I I The invention also relates'to a process I wherebyleadcontainingan. amount of anti-,

mony in excess of the percentage heretofore consideredcommerciallypractical, may

' be treated to separate the antimony in a Application filed November12,11921f ste m. I 1

- condition easily andeconomically mattin 1 to "metallic'f antimony in aI practically pure state 'by promoting; the [separation of the antimonyas 'avolatile oxide and at'the same time retardingthe formation ofthestable and higher or-pentoxide ofantimony which appears'asaslagordross. I I

The invention also relates to the'remov-al of copper from. bullion oralloy containing lead and a timbny inf'a condition practically freefromantimony, since the copper may remain in the" bath uitilpr'acticallyall o f the antimony has been fremovedin'the form ofeither the stable or the instableoxide of antimony. I I I v Theirrventionfurther consists in the new and novel fea'tures of operationand the originai mngements and combinations of steps in I the" process".hereinafter' described and more particularly set forth in theclaims.

According to; our improved process 'the "lead bullion or. alloy'to betreated containing, for example, from seventeen to twenty per cent ofantimony {from four tofiveper cent of tinffrom one to two per cent ofcopper, together with} some old, silver and perhaps small quantities ofarsenic, is nielted and raisednapidly to a bright red heat in' an oxidizng atmospherej 'The' 1 tempera- I ture m rangeffr'om: 1.200 to 1700 F.'de: pending somewhat on the compositionofthe First the tin oxidizedandis skinnned off as quickly 7 as] it. is formed in appropriatequantities and preferably with as little disoxidize; theamountotfumetending to increase as 3th? tin is. removed. Any ox de ofleadthat is. formed immediately combines with I the metallic antimonypresent the,

s5 turbance .toQthie surfaceof the bath as practicalQ .Thefantimony andthe lead begin to antimony in the bath at least within certain ranges,but is determined apparently by other factors. Preferably it is removedregularly in order to prevent interference with the continued rapidoxidation of the remaining antimony which continues to rise from thebath as a fume. The temperature of the bath is maintained at a pointwhich will prevent liquation of the copper and .will cause continuousand rapid oxidation timony has been greatly reduced and the quantity oflead oxide or litharge correspondingly increased, it "may combine withthe instableor volatile oxide of antimony. to form the higher orstablei' oxide of antimony.

After the total percentage of antimony in the bath has been loweredto-about five to seven per cent, the antimony slag or dross begins toform much more rapidly .metals may be carried out in any well andappears in greatly increased quantity.'

Atthis point the antimony fume still rises from the bath, although inreduced quan-- tity, but as the percentage of antimony isgraduallyreduced by removal of the'dross,

the volume of the fume gradually decreases until it practically ceaseswhen the percentage of antimony has been reduced approximately to threeper cent. The remaining antimony is removed in the usual manner, solelyby causing the formation of an antimony dross which is removed byskimming.

In actual operation an analysis of the contents of the bath taken atintervals shows a very rapid reduction of the antimony with rapidconcentration but practically no loss of the lead and slight reductionof the copper and of the other impurities contained in the bullion oralloy,for example, an analysis taken in actual operation after the tinskim had been removed and at the period when the antimony fume wasbeginnlng to pass ofi in its maximum volume was as follows:

Au. Ag. Pb. Cu. Sb. Sn. As.

. Per Ounces. Ouncgs. cent a gal.

After a period of treatment according to the process above set forth theanalysis of the same charge was as follows;

Au. Ag. Pb. on. Sb. Sn.

Ounces. Ounces.

Analysis discloses a gradual enrichment of the bath in the gold, silver,copper and lead contents and a decrease of the anti mony and "similarmetals, the antimony being removed largely by volatilizationz" Substaptially all of thetin is removed as a tin s ag and theantimony fume ispractically free therefrom. 1 Any copper that;

'may be present in the bullion or alloy, however, is largely retained inthe bath durknown manner.

Preferably a revcrberatory' furnace of standard construction is used forcarrying out our process, although it is obvious that any form offurnace employed for, the softenlng of lead may be utilized. Theantimony fume which separates from the bath is collected and condensedin fines or in a bag house or in any other well known manner. Theproduct recovered is a commercial oxide of antimony that is unusuallyfree from impurities. If desired, this oxide may be reduced to metallicantimony or other "commercial products may be derived therefrom, such asantimony sulphide and others.-

By our improvedprocess practically pure antimony in commercial form maybe recovered directly from'lead bullion having a relatively highantimony content. This is accomplished by taking advantage of theselective action of litharge as formed in the bath, due to the fact notheretofore recog nized that the greater part of the antimony in excessof a relatively small and practically fixed percentage would separate asa fume. Antimony dross or slag formed in the usual manner carries overfrom two to four times as much lead as antimony, and

circumstances, :it has been customary to add refined'lead or'lit'hargeto the bath in' order to facilitate the -formatioi1 oi" the antimonydrossuwithin a; reasonable --time.. Gonse from-ten to thirty perv centor more oif antimony are treated readil and successfully. Someadross *isproduced yr'our-1process,.-bu't it is relatively iinsignificent -inamount. -Insteadzof dross We obtain a commercial anti monya product of ahigh degreewof purity 3 Which is produced rapidly andin large.

quantities directly from.-the softening bath.

antimonyin "excess of a? relatively fixed pergcentage not exceeding 7per cent is removed -as a fume, and collecting said fume. v I

4'. The process of recovering oxide of antivmony .ofcommercialpurity-{from lead bul- 70 of antimony, kwhich c'onsist's in'heatingthelion containing relatively high percentages bullion under oxidizingconditions to ani' appropriate temperature above a red heat tocauseucontinuous separation of the antifreefrom' lead, and maintainingsaid temmony'ifrom thebath as a: fume substantially 5 1 peraturelxuritilithe antimony is reduced'to 1 antimony dross] in substantialamount.

torecov'ef oxide of antimony. suhstantially'l.

approximately 5-1 per .I cent With'out .formi'ngf 5. Th6 process of:treating .lead bullion containing antimony in excess of 5 per' cent aThe losses incidental to the formation of stable. oxides otyantimony andtheir :TQHIOViLl fromwthe bath as ahtimon'y skimmings, to gether ;Wit l1th8fiddltl0l1ll costrnecessi'tatede stantially allof-the excess'antimonyi'as a by sub'sequent treatment to. remove impur-u fume,thenmaintaining an appropriate'temities and recover values are-almost:entirely 1 free from lead, Which consists inllheating the bullion to-an appropriate temperature -under oxid1z1ng conditions to-removesub-1' c --perature simultaneouslyito volatilize: and" I avoided."Also-anycopper thatwmay he contained 'in the bullion is recoveredipractically' free from antimony compcunda-awhereby expensive steps inits subsequent treatment are avoide'd with iasubstantial saving in cost.i. ii. i i 7.

Having thus described our invention, We claim:

1. The process of recovering commercially pure antimony oxide directlyfrom lead bullion containing antimony in excess of a relatively fixedpercentage that forms a stable oxide of antimony in quantity in thepresence of ,lead, which consists the bullion, heating the bath'underoxidizing conditions to an appropriate temperature to effect continuousvolatilization of the excess antimony, and maintainin said temperatureuntil substantially all 0 the excess intimony is removed from the bathas a ume.

2. The process of removing antimony from lead Which consists in treatinglead bullion containing a high percentage of antimony under oxidizingconditions at an appropriate temperature above a red heat .to eitect'continuous rapid oxidation and in melting dross,theantimonys =until the.antimonyconv tent is reduced, to approximately ,3 percent,

and removing the remaining. portion of the.

antimony as-a dross.-.: 4

6. In the art 'of treating lion containing tin and v a ;relatively hlghapercentage of antimony, which consists in melting the bullion, oxidizingthe tin and removing the same from the bath as a dross, heating the bathunder oxidizing conditions to an appropriate temperature to producecontinuous oxidization and volatiliz'ation" of I the antimony in theform-of a fume substantially free from lead, maintaining sa dtemperature until the antimony content 1s reduced'below 7 per cent, andcollecting said fume. v 7. In the art of treating impure lead bullioncontaining tin, antimony and copper, the process whichv consists inmelting the bullion, oxidizing substantially all of the tin and removingthe same as a dross, malntaining the bath at an appropriate temperatureand under oxidizing conditions to form a volatile oxide of antimony freefrom oxides of tin and lead until the antimony is" reduced toapproximately 5 per cent, oxidiz- ;ing the remaining portion of theantimony at an appropriate temperature to form a dross, then reducingthe temperature of the bath to cause the liquation of the copper, andseparating the lead and the copper.

8. The process of treating lead containing copper and antimony whichconsists ,in melting the material to be treated, maintaining the bathabove 1200 F, removing under oxidizing conditions substantially all ofthe antimony in excess of seven per cent as a volatile oxide in the formof a fume, removingthe remaining portion of the antiimpure "leadjibulmony as a stable oxide in the form'of a slag and then cooling the bathto separate the vcopper as a, dross.

10. In the art of treating iinpure bullion i containing lead," tin andantimony the process which consists in melting the bu lion,

jheating the fbath to temperature above percentage 1200 F. in anoxidizing atmosphere, causing the tin to separate as a dross until theof tin is less than one per cent, maintaining the bath at an appropriatetemperature and under oxidizing conditions to form a volatile oxide ofantimony and causing the same to separate from the bath as a fume freefrom oxides of tin and lead.

11. In the art of treating impure bullion containing lead, tin, antimonyand copper the process which consists in melting the bullion, heatingthe bath to a temperature above 1200 F. in an oxidizing atmosphere,

causing the tin to\ separate as a dross untilmines;

under oxidizing condiand causing the same to separate from the I bath asa fume free from oxides of tin and 'lead until the antimony content isreduced approximately to 5 per cent, oxidizing and removingsubstantially all of the-remaining portion of the antimony as a dross,reducing the temperatiire of the bath to cause liquation of the copperand separating the lead and, thecoppen.

12. The process of removing antimony from lead containing relativelylarge percentages of antimony, which consists in melting the metal underoxidizing conditions, maintaining the bath at or above a lithargeproducing temperature, utilizing the litharge to oxidize the antimony toa volatile oxide, the formation of excessive amounts of dross oflitharge and antimony being thereby limited, and removing the volatileantimony oxide in the form of" a fume as it is formed. v

Signed at Crockett, in the county of Contra Costa and State ofCalifornia, this 3rd day of November, A. D. 1921.

BURT o. 'STANNARD. CALVINW. HAFFEY.

